The present invention generally relates to a method and an apparatus for determining fuel pressure and more particularly, to a method and an apparatus for determining the amount of pressure resident within a fuel rail member without the use of a pressure sensor, effective to determine the length of time necessary to activate at least one fuel injector, thereby allowing an engine to operate in a desirable and efficient manner.
Vehicles typically include an internal combustion engine having at least one (normally several) selectively activated fuel injectors which are adapted to receive fuel and to inject the received fuel into piston-containing cylinders, effective to allow the fuel to be combusted in the cylinders and to cause the movably contained pistons to be moved in a desired and torque-producing manner. In order to allow the engine to operate in a desired and efficient manner and in order to reduce the emission of undesired constituents which are formed by the combustion of the fuel, it is desirable to regulate the amount of fuel which is injected into the cylinders. This regulation is normally achieved by regulating or controlling the amount of time during which the injectors are xe2x80x9cactivatedxe2x80x9d (e.g., are injecting fuel into the cylinders) according to one of several methodologies.
Each of these methodologies requires the use of a quantity which is equal to the amount of fuel pressure which is resident within a fuel delivery member or assembly (e.g., a xe2x80x9cfuel railxe2x80x9d member or assembly) which is physically coupled to a source of fuel and to the injectors and which selectively communicates the fuel to the injectors. More specifically, this pressure quantity is typically provided by a fuel pressure sensor which is resident within the fuel delivery member.
While a fuel pressure sensor does provide the needed pressure measurement or quantity, it suffers from some drawbacks. For example, the sensor is relatively expensive and may require maintenance or replacement, thereby increasing the overall cost of operating and servicing a vehicle.
There is therefore a need for a method and an apparatus for determining the amount of fuel pressure existing within a fuel delivery member in a manner which overcomes some or all of the previously delineated drawbacks of prior methods and apparatuses.
It is a first object of the present invention to provide a method and an apparatus for determining the amount of fuel existing within a fuel delivery member in a manner which overcomes some or all of the previously delineated drawbacks of prior methods and apparatuses.
It is a second object of the present invention to provide a method and an apparatus for determining the amount of fuel existing within a fuel delivery member in a manner which overcomes some or all of the previously delineated drawbacks of prior methods and apparatuses and which obviates the need for a pressure sensor or transducer.
It is a third object of the present invention to provide a method and an apparatus for determining the amount of fuel existing within a fuel delivery member in a manner which overcomes some or all of the previously delineated drawbacks of prior methods and apparatuses and which may be used to determine a desired amount of time for which at least one fuel injector is to be selectively activated.
According to a first aspect of the present invention, an apparatus for inferring an amount of pressure within a fuel rail and for using the inferred amount of pressure to control a fuel injector is provided.
According to a second aspect of the present invention, an assembly is provided. The assembly comprises a plurality of fuel injectors; a source of fuel; a first member which is coupled to the source of fuel and to the plurality of fuel injectors; a second member which is coupled to a source of voltage which provides a certain amount of voltage to the source of fuel and to the first member and which causes at least some of the fuel which is resident within the source of fuel to be communicated to the first member, thereby creating a certain pressure within the first member; and a controller assembly which is coupled to the second member and to the plurality of fuel injectors, which determines a desired amount of fuel required for each of the plurality of fuel injectors, which senses a certain speed, which determines a certain number of the plurality of fuel injectors which are to be activated during a certain interval of time, which calculates a desired fuel rate, and which uses the desired fuel rate and the certain amount of voltage to infer the amount of the pressure which is resident within the first member.
According to a third aspect of the present invention, a method is provided. The method deduces an amount of pressure resident within a fuel delivery member and includes the steps of calculating a desired fuel rate; determining a certain voltage; and using the desired fuel flow rate and the certain voltage to deduce the amount of the pressure.
These and other aspects, features, and advantages of the present invention will become apparent from a reading of the following detailed description of the preferred embodiment of the invention and by reference to the following drawings.